During the first year of this project efforts have been directed in two main areas: To determine if a mixture of bovine brain gangliosides (BBG) alters the development of these neurons in vitro, and (2) to determine if other neuronotrophic agents enhance trigeminal ganglia neuritogenesis in vitro. To determine the effect of gangliosides on survival and axonal regeneration of trigeminal neurons, ganglia were dissociated and fed with medium containing various concentrations of a mixture of BBG and maintained at 35 degrees C in medium on collagen- coated coverslips in Maximow chambers for up to 2 weeks. Quantitative microscopic evaluation was performed to determine neurite length and number per perikaryon. Two neuronal populations were examined: small bipolar neurons and larger, less frequent multipolar neurons. The presence of BBG did not alter the neuronal numbers of neurite lengths of either population. To determine if neurotrophic agents would stimulate neuritogenesis of trigeminal neurons in vitro, we examined the effects of Nerve Growth Factor (NGF) on trigeminal development. Accordingly, cell were treated with several concentrations of NGF and maintained 6 days in vitro. These studies demonstrated that, under these culture conditions and over this range of concentrations, NGF did not alter neuronal survival. The length and number of processes emanating from the neuronal soma also remained constant. Finally, we applied a mixture of gangliosides and NGF simultaneously to trigeminal ganglia and evaluated the effect on the two neuronal populations. There was no detectable effect on bipolar cells. In contrast, this treatment produced a 3-fold increase in the length of the multipolar processes while the number of processes remained constant.